Percentage Calculator

Written byOleh Soloninupdated 5 October 2026

What to work out

Number A

For a change, the starting value; for what percent, the part.

Percentage, %

Result

Answer750
Working5,000 × 15 ÷ 100 = 750
If A is P%, the whole is33,333.33

Pick the problem and the formula appears with the answer

Eight percentage problems in one calculator: a percentage of a number, what percent one number is of another, the whole from a percentage, adding and subtracting a percentage, change, difference and reverse percentage.

Percentage questions come in several shapes and people mix them up constantly. 'What is 15% of 200?', 'what percent is 30 of 200?' and 'if 30 is 15%, what is the whole?' use the same numbers for three different calculations.

So you choose the problem first, and the calculator shows the working with your numbers filled in as well as the answer.

How to use

Choose the problem: a percentage of a number, what percent, add or subtract a percentage, change, difference or reverse percentage.
Enter the numbers; the fields adapt to the problem.
Read the answer and the working line, rounded to two decimals.

Formulas for every percentage problem

A percent is a hundredth, so every formula multiplies or divides by 100. What matters is the base the percentage is taken from: the whole, the old value, or the number after the increase.

Examples worked out with this calculator.
Problem	Formula	Example
Percentage of a number	A × P ÷ 100	15% of 5,000 = 750
What percent A is of B	A ÷ B × 100	750 of 5,000 = 15%
The whole from its percentage	A ÷ P × 100	750 is 15% of 5,000
Add a percentage	A × (1 + P ÷ 100)	5,000 + 15% = 5,750
Subtract a percentage	A × (1 − P ÷ 100)	5,000 − 15% = 4,250
Change from A to B	(B − A) ÷ \|A\| × 100	5,000 → 4,000 = −20%
How much more A is than B	(A − B) ÷ \|B\| × 100	5,000 is 25% more than 4,000
Before a percentage was added	A ÷ (1 + P ÷ 100)	5,750 including 15% was 5,000

What this calculator shows

The answer to the chosen problem, rounded to two decimals
The formula with your numbers filled in
For a percentage of a number, the reverse answer as well

What to keep in mind

Percentages are treated as parts per hundred, so 15 means 0.15.
For percentage increases and decreases between two values, the percent change calculator is the right tool.

FAQs

How do I calculate 20% of a number in my head?

Move the decimal one place left to get 10%, then double it. For 85: 10% is 8.5, so 20% is 17.

What is 15% of 200?

30. And to close the loop the other way, if 30 is 15% of something, that something is 200.

Why is a 20% discount followed by 20% off again not 40% off?

The second discount applies to the already-reduced price. £100 becomes £80, then £64 — a 36% total reduction, not 40%.

Can percentages go above 100?

Yes. 150% of 40 is 60. Anything above 100% simply means more than the original whole.

What is 15% of 5,000?

750. Multiply 5,000 by 0.15, or divide by 100 and multiply by 15 — the two routes meet at the same number.

How do I estimate a percentage mentally?

Work through one percent. Divide by a hundred, then multiply by the share you need: one percent of 5,000 is 50, so 15% is 15 × 50 = 750 and 3% is 150.

Worked example

A restaurant tip

Input: 15% of 200

Output: 30

Note: A useful mental check: 10% is 20, half of that is 10, and 20 + 10 gives the same 30.

Useful links

All tools in Math & Statistics

Percentage Calculator

Result

Related tools

Percent of a Number Calculator

What Percent Is X of Y

Add a Percentage Calculator

Subtract a Percentage Calculator

Percent Difference Calculator

Reverse Percentage Calculator

Useful links